2.5V Zener Diode
Before anything else, the Zener diode is a "diode". It will flow the current when properly polarised (as a regular diode)! Once the thresold reached (~0.6V) the current flows.
It is the reverse way which is very interesting! As normal diode, the Zener diode start to block the current flow when reverse voltage is applied accross the diode. Once the reverse voltage is high enough (the "avalanche voltage") then the Zener Diode allow the reverse current to flow through it!
The Zener diode is very appreciated for its reverse avalanche voltage because it allows protect circuit against overvoltage or to easily creates a reference voltage.
The Zener diode must be used in series with a resistor because the current flowing through the diode must be limited when the avalanche voltage is reached. Zener diode datasheet usually contains the maximum power allowed (and/or max current).
- Ref: 1N5222B-TR
- Vzener: 2.5V
- Forward Voltage (Vf): 1.1V @ 200mA
- Reverse Leakage Current: 100µA @ 1V
- Pmax: 500mW
- Impedance: 30 Ohms
- Tolerance: 5%
- DO-35 (traversant)
- 1N5222B-TR Technical Datasheet (pdf)